Heat stress monitors have been used to set protective limits for workers in stressful environments. The monitors have included a dry bulb thermometer to measure ambient temperature, a wet bulb thermometer to include the effect of humidity, and a globe radiant sensor to include the effect of sunlight or other light or infrared emitting hot objects, such as a furnace. These monitors have been used to help determine stay times and warn workers working in hot and humid environments. Description of some of the serious disorders arising from working in hot and humid environments and the heat stress monitors used to evaluate those environments is provided in papers published by the US Army and US Navy, including OPNAVINST 5100.19D, Chapter B2 and Table B2-A-2, Oct. 5, 2000, “Prediction Modeling of Physiological Responses and Human Performance in the Heat,” by Kent B. Pandolf, US Army Research Institute of Environmental Medicine, Natick Mass., and “A physiological strain index to evaluate heat stress,” by Daniel S. Moran, et al, US Army Research Institute of Environmental Medicine, Natick Mass., (“the Army/Navy references”), incorporated herein by reference.
Heat stress monitors have required periodic attention because water for the wet bulb thermometer needed frequent replenishment and because data needed to be frequently recorded either by a person reading a display or through a hard wired connection to a separate display system. Thus a better scheme for heat sensor monitoring is needed to eliminate these problems, and this scheme is provided by this patent application.